How to change the grey background with a film icon on html5 video in android Webview

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http://stackoverflow.com – I'm developing an android app which load a website via webview, everything works fine and the video can play. However, the video when in idle state show a grey background and a film icon in center, when in loading state it show a grey background and a loading icon. It doesn't suit with my website, so i want to change it color to black, or if possible, change it into some image. How can i do it? (HowTos)